Abstract: An X-ray tube includes a rotor body having an outer sleeve of copper and an inner sleeve of steel, the two sleeves being joined by brazing. A black coating is applied to the outer surface of the copper sleeve and the inner surface of the steel sleeve, as well as to the outer surface of a copper bearing housing concentrically disposed within the rotor body. A steel spindle is concentrically and rotatably supported within the housing by a bearing structure and is rigidly affixed to the rotor body to support the rotor body for rotation. The X-ray tube also includes an anode comprised of molybdenum having a coating of rhenium-tungsten. The anode is supported on a shaft comprised of a material having a low coefficient of thermal conductivity such as niobium, an alloy of niobium, molybdenum, or an alloy of molybdenum. The X-ray tube further includes a bearing structure having portions lubricated by lead.

Abstract: An x-ray tube is described including a focusing cup electrode coated with a high work function material, such as platinum or gold, to prevent the field emission of electrons from such cup. The method of applying the non-emitting coating is preferably sputtering or ion plating, but may also be electroplating followed by vacuum fusion in the case of gold or other low melting point metals.